title: Physical activity as determinant of femoral neck strength relative to load in adult women: findings from the hip strength across the menopause transition study.
abstract: Our objective was to examine associations of physical activity in different life domains with peak femoral neck strength relative to load in adult women. Greater physical activity in each of the domains of sport, active living, home, and work was associated with higher peak femoral neck strength relative to load.
  
  
  BACKGROUND
  Our objective was to examine the associations of physical activity in different life domains with peak femoral neck strength relative to load in adult women. Composite indices of femoral neck strength integrate body size with femoral neck size and bone mineral density to gauge bone strength relative to load during a fall, and are inversely associated with incident fracture risk.
  
  
  METHODS
  Participants were 1,919 pre- and early perimenopausal women from the Study of Women's Health Across the Nation. Composite indices of femoral neck strength relative to load in three failure modes (compression, bending, and impact) were created from hip dual-energy X-ray absorption scans and body size. Usual physical activity within the past year was assessed with the Kaiser Physical Activity Survey in four domains: sport, home, active living, and work. We used multiple linear regression to examine the associations.
  
  
  RESULTS
  Greater physical activity in each of the four domains was independently associated with higher composite indices, adjusted for age, menopausal transition stage, race/ethnicity, Study of Women's Health Across the Nation study site, smoking status, smoking pack-years, alcohol consumption level, current use of supplementary calcium, current use of supplementary vitamin D, current use of bone-adverse medications, prior use of any sex steroid hormone pills or patch, prior use of depo-provera injections, history of hyperthyroidism, history of previous adult fracture, and employment status: standardized effect sizes ranged from 0.04 (p < 0.05) to 0.20 (p < 0.0001).
  
  
  CONCLUSIONS
  Physical activity in each domain examined was associated with higher peak femoral neck strength relative to load in pre- and early perimenopausal women.
authors.affiliation: Geriatric Research Education and Clinical Center, VA Greater Los Angeles Healthcare System, 11301 Wilshire Blvd, Bldg B220 11(G), Los Angeles, CA, 90073, USA, takahiromori@outlook.com.
authors.forename: T
authors.initials: T
authors.lastname: Mori
authors.forename: S
authors.initials: S
authors.lastname: Ishii
authors.forename: G A
authors.initials: GA
authors.lastname: Greendale
authors.forename: J A
authors.initials: JA
authors.lastname: Cauley
authors.forename: B
authors.initials: B
authors.lastname: Sternfeld
authors.forename: C J
authors.initials: CJ
authors.lastname: Crandall
authors.forename: W
authors.initials: W
authors.lastname: Han
authors.forename: A S
authors.initials: AS
authors.lastname: Karlamangla
mesh_terms: D015502:Absorptiometry, Photon / Q000379:methods; D000203:Activities of Daily Living; D000328:Adult; D000375:Aging / Q000502:physiology*; D015519:Bone Density / Q000502:physiology; D019245:Compressive Strength / Q000502:physiology; D005260:Female; D005272:Femur Neck / Q000502:physiology*; D006306:Health Surveys; D006801:Humans; D008593:Menopause / Q000502:physiology*; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D013177:Sports / Q000502:physiology; D016474:Weight-Bearing / Q000502:physiology; D016387:Women's Health